How screwed is my K-member?

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poconos_power

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Hey all, so as part of my Duster project I got some advice here to get a 73+ kmember and control arms, and everyone here was kind enough to help me find them initially, which was really cool. However, I'm in the process of welding the seams on my k-member and for some reason I decided to distract myself and test fit the pivot pins. Good thing I did, as it turns out the pin on the passenger side just flops around in the hole. Upon closer inspection it seems to hole is not exactly a circle anymore, and there is some bunched up metal and cracked welds. I've seen some mentions here that such a thing could be fixable, but I'm not quite sure if I should take a crack at it, or how to do it while keeping my geometry from getting all messed up. Was wondering, based on the picture below, what you all think. Tried to capture the shadows to show where the metal is bunched up.

I'll also add, I've basically learned to weld to start on this project, and I'm still learning with each weld. To call me an amateur welder is an insult to amateurs. That said, I'm willing to try some things because my other option is to find a new kmember and start over. For some reason they were everywhere online last year and now, not so much :(

IMG_20260112_204116389_HDR.jpg
IMG_20260112_204111856_HDR.jpg
 
I’d probably look for a different k-member. They can be found cheap. 100 bucks or less.

If you’re as new to welding as you say you are I would do any ‘fixes’ yourself. This piece is Important for your safety and the safety or vehicles around you.
 
Harder to tell in the photos, but the whole is definitely elongated, hence the bunched up metal I'm pretty sure.

Seems like 73+ k-members have dried up for now, guess I've got to wait to see what comes up. Unless someone has one kicking around...?
 
If you can get the tube out of the k-frame easy enough i would get a new tube in the right size, temp mount the k-frame and put the torsion bar in to align the tube and weld a new one in.. you will be out like $20 and a hours worth of work... the tube isn't special.. No idea at all how they did that though other than if they didn't tighten the pivot and it spent 15 years moving around which is easily possible...

P.S. get a friend to weld it if you are worried.. but that you would do pretty hot and it doesn't need to be perfect..
 
That can be fixed. Cut it out and replace the tube. If you are just starting to weld practice on some stuff the same gauge. If you don't feel good enough about welding it yourself just get it tacked together and have it done. But really that is an easy fix.
 
Icetech said:
If you can get the tube out of the k-frame easy enough i would get a new tube in the right size, temp mount the k-frame and put the torsion bar in to align the tube and weld a new one in.. you will be out like $20 and a hours worth of work... the tube isn't special.. No idea at all how they did that though other than if they didn't tighten the pivot and it spent 15 years moving around which is easily possible...

P.S. get a friend to weld it if you are worried.. but that you would do pretty hot and it doesn't need to be perfect..
Click to expand...

Hellrats said:
That can be fixed. Cut it out and replace the tube. If you are just starting to weld practice on some stuff the same gauge. If you don't feel good enough about welding it yourself just get it tacked together and have it done. But really that is an easy fix.
Click to expand...
How do you recommend he locates the new tube before welding?
 
You can use straight tube and an old control arm pivot. Then heat the tubing and form it around the pivot. Or just weld up washers like is shown above in the link. Easy peasy.
 
I wouldn’t be surprised at all if other than the cracked welds that K looked exactly like that from the factory.

They were not precision pieces, the factory welds were not great and occasionally awful.

When I re-do a K I seam weld and gusset it, including the pivot tube. An HD washer works well, IIRC an HD 1-1/8” is what I used.
IMG_8166.jpeg


@Jim Lusk will have better details on repairing the damaged pivot tube, but it’s not an uncommon repair at all. The factory welds weren’t good.
 
Keep in mind welds can look sloppy, as long as they penetrate the metal they are good.

Grinding them to make them look better doesn't make them any stronger.
 
Looks like a lot of guys think it can be fixed, which I'm willing to explore, the other option is to toss this kmember. So, I should mention that the pin goes all the way in, way past how far it goes in on the side that's still good, and it can kinda flop around in the tube. I do have the FFI reinforcement kit that was planned to go on, and I now see why it reinforces the tubes, wow. So if I do that, I guess I'll get the right spacing potentially, but I don't want the only thing keeping the pin in place being how tight I wrench down the threads on the nut. That feels like a recipe for disaster.

If I somehow extract that tube and make it right by bashing on my pivot pins. Is the only way to get it in straight to fully install the kmember in the car? I still have the old 1970 suspension in the car to hold it up so I can roll it around while I do other projects. I suppose any more detailed guidance on approaches would be appreciated. I'm really wanting to fix the tube because right now it does nothing to locate the pin, it's just a spacer so that when I crank the nut down the walls stay where they need to be.

I suppose another option is to take my /6 kmember out of the car and try to extract a good tube and see if I can weld that in somehow? I guess that's my last resort as if I do that and it doesn't quite go to plan, I'll be dead in the water looking for a new kmember with the car stuck on the lift.

Well, all that said, if anyone hears of a good 73+ kmember, let me know, as right now starting over with a good one is totally not off the table.
 
Pass a pin through one side, and measure. Pass a pin through the other hole, and see how much is worn. Lay some weld in there and ream it to fit, and send it.

It's like that because it was run without the bolt being tight. You tighten your bolts, and that won't happen. Don't worry about it being super precise, because it NEVER was. That's why the car has alignment features and LCA bushings. The bushings never locate anything perfectly, that's by design. If the pin is off a few degrees, it's going to be just like it was when new.

So, lay some bead in there, clean it out until the shell of the tube is the same thickness all 'round, and carry on. The pin doesn't use most of the area in there anyway. The nut pulls the shoulder up tight to the tube, and the bushing does bushing things. It's not a roller bearing for a reason: it was never meant to be, and a couple degrees there won't create bump steer issues or anything like they will in an idler arm.


What is factory frame tolerance in these cars? 1/8"?
 
Early pin tubes appear to not be tapered, so it's probably not a big deal. If they are wallowed out they probably should be replaced, but you need a jig to get them back in the right location. I have a jig. I've also considered the idea of moving them up in the K-member just a little, but since I don't have the calculations and all to see what effect that would cause I have resisted the temptation. The problem with thick washers on the outside (primarily the back side) is that it could relocate the LCA which might reduce the available amount of positive caster. I cut the bottom of the K-member open and weld the tubes on the inside. The factory was under welded the tubes. This is from a K-member I picked up that had a bad twist to it and was no longer square. In order to straighten it I cut the bottom off. I took this on just to see if I could do it...

DW213185.JPG
 
While it looks like a daunting task and probably is, it's a 50 + year old k member and they all are. Pretty much all of them you find for sale will have some wear to them. I'd fix it or have it fixed for me after fully researching the task.

The first thing I would do is figure out if the k frame is twisted or not. Then I would figure out if just the tube is elongated from wear or if the hole in the k frame the tube ifts in is elongated as well. Time to get your calipers out and start measuring to check it all out.
 

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